Most of today's CT (computed tomography) scanners use beam shapers, often called bowtie filters, to adapt the intensity profile of the scanner's x-ray (that is incident on a patient) to the thickness profile of the patient to be imaged. The so adapted, in general spatially non-uniform, x-ray profile helps secure a number of advantages: less patient dose, less x-ray scatter, more homogeneous image quality, and reduction of the dynamic range requirements for the scanner's detector by using lower intensity in certain parts of the beam, especially in those parts in direct irradiation areas. Some beam shapers allow selection from a (usually very limited) set of available filter bodies that are based on a rough patient classification (e.g. child, adult, etc).
There are also “dynamic” beam shaping devices that afford a high degree of adaptability of their filter bodies to individual body shapes. Examples of such filters are described in Applicant's WO 2013/001386 or U.S. Pat. No. 6,453,013. However it has turned out that calibration procedures (that is, the acquisition of gain correction images or “air scans”) for imagers having such (highly) adaptable beam shapers are remarkably cumbersome.